1. Field of the Invention
The present invention relates to a pneumatic hand tool. More particularly, the present invention relates to a pneumatic hand tool which is compact in weight and low cost.
2. Description of Related Art
The current available pneumatic hand tool is shown in FIG. 6, which includes a body (60), a cylinder (61), a rotor (62), a bearing (63), a sealing cap (64) and a control knob (65). The conventional pneumatic hand tool as shown is characterized in that the sealing cap (64) is firmly secured to a rear side of the body (60) so as to tightly encase and position the cylinder (61), the rotor (62) and the bearing (63) inside the body (60). The sealing cap (64) is provided with an inlet passage and a pair of mutually corresponding air conducting passages incorporative with the control knob (65) to control and adjust the air path and air volume entering the cylinder (61). Accordingly, the rotation direction and rotational torque of the pneumatic hand tool are controlled. However, the conventional pneumatic hand tool has contained some improvable defects, such as:
1. Poor airtight capability: Due to the control knob (65) and the cylinder (61) are separated, so as there is a possibility that the clearances existed between the control knob (65) and the cylinder (61) when they are assembled inside the body (60), which results in a poor airtight effect;
2. High manufacture cost: Due to the control knob (65) and the cylinder (61) are separated, so as the body (6) is limited to be made of a metallic material to enhance its airtight capability, and that could cause a higher manufacture cost; and
3. Inconvenience in operation: Due to the control knob (65) and the cylinder (61) are separated, so as the body (6) is limited to be made of a metallic material to enhance the safety requirement, and that leads to the increase of weight of the hand tool, further to influent the operation of the hand tool.
The present invention is intended to improve the above mentioned drawbacks of the conventional pneumatic hand tool. The present invention provides improved solutions to the problems of poor airtight capability, high manufacturing cost and inconvenience in operation.